System and method for arranging equipment in a data center

ABSTRACT

A system and method for providing a layout of equipment in a data center, the equipment including a plurality of equipment racks, and at least one rack-based cooling provider. In one aspect, the method includes receiving data regarding airflow consumption for each of the plurality of equipment racks and cooling capacity of the at least one cooling provider, determining a layout of the data center, displaying the layout of the data center. In the method determining a layout can include pairing each equipment rack of the plurality of equipment racks with another equipment rack of the plurality of equipment racks based on airflow consumption of each of the plurality of equipment racks to create a plurality of pairs of equipment racks, arranging the pairs of equipment racks to form a two-row cluster of equipment racks based on the airflow consumption value of the equipment racks.

RELATED APPLICATIONS

This application is a continuation of, and claims the benefit under 35U.S.C. § 120 of, U.S. application Ser. No. 12/437,734, filed May 8,2009, now U.S. Pat. No. 8,219,362, entitled “SYSTEM AND METHOD FORARRANGING EQUIPMENT IN A DATA CENTER”, which is herein incorporated byreference in its entirety.

BACKGROUND

1. Field of the Invention

At least one embodiment in accordance with the present invention relatesgenerally to systems and methods for data center management and design,and more specifically, to systems and methods for managing data centerair flow and energy usage and for arranging equipment in a data centerbased on air flow and energy usage.

2. Discussion of Related Art

In response to the increasing demands of information-based economies,information technology networks continue to proliferate across theglobe. One manifestation of this growth is the centralized network datacenter. A centralized network data center typically consists of variousinformation technology equipment, collocated in a structure thatprovides network connectivity, electrical power and cooling capacity.Often the equipment is housed in specialized enclosures termed “racks”which integrate connectivity, power and cooling elements. In some datacenter configurations, rows of racks are organized into hot and coldaisles to decrease the cost associated with cooling the informationtechnology equipment. These characteristics make data centers a costeffective way to deliver the computing power required by many softwareapplications.

Various processes and software applications, such as the InfrastruXure®Central product available from American Power Conversion Corporation ofWest Kingston, R.I., have been developed to aid data center personnel indesigning and maintaining efficient and effective data centersconfigurations. These tools often guide data center personnel throughactivities such as designing the data center structure, positioningequipment within the data center prior to installation andrepositioning, removing, and adding equipment after construction andinstallation are complete. Thus, conventional tool sets provide datacenter personnel with a standardized and predictable design methodology.

SUMMARY OF THE INVENTION

A first aspect of the invention is directed to a computer-implementedmethod for providing a layout of equipment in a data center, theequipment including a plurality of equipment racks, and at least onecooling provider. The method includes receiving data regarding airflowconsumption for each of the plurality of equipment racks and coolingcapacity of the at least one cooling provider, storing the received datadetermining a layout of the data center, and displaying the layout ofthe data center. Determining a layout may include pairing each equipmentrack of the plurality of equipment racks with another equipment rack ofthe plurality of equipment racks based on airflow consumption of each ofthe plurality of equipment racks to create a plurality of pairs ofequipment racks, determining a combined airflow consumption value foreach of the pairs of equipment racks, arranging the pairs of equipmentracks to form a two-row cluster of equipment racks based on the combinedpower consumption value of the equipment racks, wherein each pairincludes an equipment rack in a first row of the cluster and anequipment rack in a second row of the cluster, and determining alocation of the at least one cooling provider in the cluster.

In the method, pairing each equipment rack may include pairing agreatest airflow consuming equipment rack with a least airflow consumingequipment rack, and pairing a second greatest airflow consumingequipment rack with a second least airflow consuming rack. Arranging thepairs of equipment racks may include identifying a rack pair having agreatest combined airflow consumption value, a rack pair having a leastcombined airflow consumption value, and a rack pair having a secondleast combined airflow consumption value, and positioning the rack pairhaving the greatest combined airflow consumption value in a middleposition of the cluster, arranging the rack pair having the leastcombined airflow consumption value at a first end of the cluster, andarranging the rack pair having the second least combined powerconsumption value at a second end of the cluster.

In the method, determining a location for the at least one coolingprovider may include determining an interior position for the at leastone cooling provider adjacent two equipment racks. The method mayfurther include receiving information related to a desired coolingredundancy for at least one of the equipment racks, and determining alayout may include determining a layout based at least in part on theinformation related to a desired cooling redundancy. After determiningthe layout, the method may include providing an optimized layout usingan optimization routine. The method may also include positioning theequipment in the data center in accordance with the determined layout.

Another aspect of the invention is directed to a system for providing alayout of equipment in a data center, the equipment including aplurality of equipment racks, and at least one cooling provider. Thesystem includes a display, a storage device, an interface, and acontroller coupled to the display, the storage device and the interfaceand configured to receive through the interface data regarding airflowconsumption for each of the plurality of equipment racks and coolingcapacity of the at least one cooling provider, store the received datain the storage device, determine a layout of the data center, anddisplay the layout of the data center on the display. Determining alayout may include pairing each equipment rack of the plurality ofequipment racks with another equipment rack of the plurality ofequipment racks based on airflow consumption of each of the plurality ofequipment racks to create a plurality of pairs of equipment racks,determining a combined airflow consumption value for each of the pairsof equipment racks, arranging the pairs of equipment racks to form atwo-row cluster of equipment racks based on the combined airflowconsumption value of the equipment racks, wherein each pair includes anequipment rack in a first row of the cluster and an equipment rack in asecond row of the cluster, and determining a location of the at leastone cooling provider in the cluster.

In the system, pairing each equipment rack may include pairing agreatest airflow consuming equipment rack with a least airflow consumingequipment rack, and pairing a second greatest airflow consumingequipment rack with a second least airflow consuming rack. In thesystem, arranging the pairs of equipment racks may includes identifyinga rack pair having a greatest combined airflow consumption value, a rackpair having a least combined airflow consumption value, and a rack pairhaving a second least combined airflow consumption value, andpositioning the rack pair having the greatest combined airflowconsumption value in a middle position of the cluster, arranging therack pair having the least combined airflow consumption value at a firstend of the cluster, and arranging the rack pair having the second leastcombined airflow consumption value at a second end of the cluster.

In the system, determining a location for the at least one coolingprovider may include determining an interior position for the at leastone cooling provider adjacent two equipment racks. Further, thecontroller may be configured to receive information related to a desiredcooling redundancy for at least one of the equipment racks, and may beconfigured to determine a layout based at least in part on theinformation related to a desired cooling redundancy. The controller maybe further configured to determine an optimized layout using anoptimization routine having the determined layout as an input.

Another aspect of the invention is directed to a computer readablemedium having stored thereon sequences of instruction includinginstructions that will cause a processor to receive data regardingairflow consumption for each of a plurality of equipment racks andcooling capacity of at least one cooling provider contained in a datacenter, store the received data in a storage device, determine a layoutof the data center, and display the layout of the data center on adisplay. The instructions for determining a layout may include pairingeach equipment rack of the plurality of equipment racks with anotherequipment rack of the plurality of equipment racks based on airflowconsumption of each of the plurality of equipment racks to create aplurality of pairs of equipment racks, determining a combined airflowconsumption value for each of the pairs of equipment racks, arrangingthe pairs of equipment racks to form a two-row cluster of equipmentracks based on the combined airflow consumption value of the equipmentracks, wherein each pair includes an equipment rack in a first row ofthe cluster and an equipment rack in a second row of the cluster, anddetermining a location of the at least one cooling provider in thecluster.

In the instructions, pairing each equipment rack may include pairing agreatest airflow consuming equipment rack with a least airflow consumingequipment rack, and pairing a second greatest airflow consumingequipment racks with a second least airflow consuming rack. Further,arranging the pairs of equipment rack may include identifying a rackpair having a greatest combined airflow consumption value, a rack pairhaving a least combined airflow consumption value, and a rack pairhaving a second least combined airflow consumption value, andpositioning the rack pair having the greatest combined airflowconsumption value in a middle position of the cluster, arranging therack pair having the least combined airflow consumption value at a firstend of the cluster, and arranging the rack pair having the second leastcombined airflow consumption value at a second end of the cluster. Stillfurther, determining a location for the at least one cooling providermay include determining an interior position for the at least onecooling provider adjacent two equipment racks. The computer readablemedium may further include instructions that will cause the processor toreceive information related to a desired cooling redundancy for at leastone of the equipment racks, and determine a layout may includedetermining a layout based at least in part on the information relatedto a desired cooling redundancy. The medium may also includeinstructions that will cause the processor to determine an optimizedlayout using an optimization routine having the determined layout as aninput.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures. is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 shows an example computer system with which various aspects inaccord with the present invention may be implemented;

FIG. 2 illustrates an example distributed system including anembodiment;

FIG. 3 shows an example layout of equipment racks and coolers in a datacenter;

FIG. 4 shows a process for determining a layout of equipment in a datacenter in accordance with one embodiment; and

FIG. 5 shows a preferred layout of a cluster of equipment determinedusing a tool in accordance with one embodiment.

DETAILED DESCRIPTION

At least some embodiments in accordance with the present inventionrelate to systems and processes through which a user may design datacenter configurations. These systems may facilitate this design activityby allowing the user to create models of data center configurations fromwhich performance metrics may be determined Both the systems and theuser may employ these performance metrics to determine alternative datacenter configurations that meet various design objectives. Further, inat least one embodiment, a system will provide an initial layout of datacenter equipment and conduct a cooling analysis on the layout in realtime.

As described in U.S. patent application Ser. No. 12/019,109, titled“System and Method for Evaluating Equipment Rack Cooling”, filed Jan.24, 2008, and in U.S. patent application Ser. No. 11/342,300, titled“Methods and Systems for Managing Facility Power and Cooling” filed Jan.27, 2006 both of which are assigned to the assignee of the presentapplication, and both of which are hereby incorporated herein byreference in their entirety, typical equipment racks in modern datacenters draw cooling air in the front of the rack and exhaust air outthe rear of the rack. The equipment racks, and in-row coolers aretypically arranged in rows in an alternating front/back arrangementcreating alternating hot and cool aisles in a data center with the frontof each row of racks facing the cool aisle and the rear of each row ofracks facing the hot aisle. Adjacent rows of equipment racks separatedby a cool aisle may be referred to as a cool or cold aisle cluster, andadjacent rows of equipment racks separated by a hot aisle may bereferred to as a hot aisle cluster. As readily apparent to one ofordinary skill in the art, a row of equipment racks may be part of onehot aisle cluster and one cool aisle cluster. In descriptions and claimsherein, equipment in racks, or the racks themselves, may be referred toas cooling consumers, and in-row cooling units and/or computer room airconditioners (CRACs) may be referred to as cooling providers. In thereferenced applications, tools are provided for analyzing the coolingperformance of a cluster of racks in a data center. In these tools,multiple analyses may be performed on different layouts to attempt tooptimize the cooling performance of the data center.

In embodiments, of the invention, different cooling performance metricsmay be used to evaluate the cooling performance of a cluster. Thesemetrics include capture index (CI) and recirculation index (RI) both ofwhich are described in further detail in the applications, incorporatedby reference above. In general, for a hot aisle cluster, the captureindex indicates for each rack the percentage of the rack exhaust airthat is captured by all of the coolers in the cluster. For a cool aislecluster, the capture index indicates for each rack the percentage ofrack airflow that is supplied directly by local cooling providers.

In at least one embodiment, a model of a data center is generated anddisplayed and a cooling analysis is provided of the data center. Increating a model, in at least one embodiment, a user may define a set ofequipment racks and cooling providers to be included in a cluster, andthe system will automatically arrange the equipment racks and thecooling providers in the cluster in a manner that will satisfy coolingrequirements of the equipment racks.

The aspects disclosed herein in accordance with the present invention,are not limited in their application to the details of construction andthe arrangement of components set forth in the following description orillustrated in the drawings. These aspects are capable of assuming otherembodiments and of being practiced or of being carried out in variousways. Examples of specific implementations are provided herein forillustrative purposes only and are not intended to be limiting. Inparticular, acts, elements and features discussed in connection with anyone or more embodiments are not intended to be excluded from a similarrole in any other embodiments.

For example, according to one embodiment of the present invention, acomputer system is configured to perform any of the functions describedherein, including but not limited to, configuring, modeling andpresenting information regarding specific data center configurations.Further, computer systems in embodiments of the data center may be usedto automatically measure environmental parameters in a data center, andcontrol equipment, such as chillers or coolers to optimize performance.Moreover, the systems described herein may be configured to include orexclude any of the functions discussed herein. Thus the invention is notlimited to a specific function or set of functions. Also, thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use herein of“including,” “comprising,” “having,” “containing,” “involving,” andvariations thereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items.

Computer System

Various aspects and functions described herein in accordance with thepresent invention may be implemented as hardware or software on one ormore computer systems. There are many examples of computer systemscurrently in use. These examples include, among others, networkappliances, personal computers, workstations, mainframes, networkedclients, servers, media servers, application servers, database serversand web servers. Other examples of computer systems may include mobilecomputing devices, such as cellular phones and personal digitalassistants, and network equipment, such as load balancers, routers andswitches. Further, aspects in accordance with the present invention maybe located on a single computer system or may be distributed among aplurality of computer systems connected to one or more communicationsnetworks.

For example, various aspects and functions may be distributed among oneor more computer systems configured to provide a service to one or moreclient computers, or to perform an overall task as part of a distributedsystem. Additionally, aspects may be performed on a client-server ormulti-tier system that includes components distributed among one or moreserver systems that perform various functions. Thus, the invention isnot limited to executing on any particular system or group of systems.Further, aspects may be implemented in software, hardware or firmware,or any combination thereof. Thus, aspects in accordance with the presentinvention may be implemented within methods, acts, systems, systemelements and components using a variety of hardware and softwareconfigurations, and the invention is not limited to any particulardistributed architecture, network, or communication protocol.

FIG. 1 shows a block diagram of a distributed computer system 100, inwhich various aspects and functions in accord with the present inventionmay be practiced. Distributed computer system 100 may include one morecomputer systems. For example, as illustrated, distributed computersystem 100 includes computer systems 102, 104 and 106. As shown,computer systems 102, 104 and 106 are interconnected by, and mayexchange data through, communication network 108. Network 108 mayinclude any communication network through which computer systems mayexchange data. To exchange data using network 108, computer systems 102,104 and 106 and network 108 may use various methods, protocols andstandards, including, among others, token ring, ethernet, wirelessethernet, Bluetooth, TCP/IP, UDP, Http, FTP, SNMP, SMS, MMS, SS7, Json,Soap, and Corba. To ensure data transfer is secure, computer systems102, 104 and 106 may transmit data via network 108 using a variety ofsecurity measures including TSL, SSL or VPN among other securitytechniques. While distributed computer system 100 illustrates threenetworked computer systems, distributed computer system 100 may includeany number of computer systems and computing devices, networked usingany medium and communication protocol.

Various aspects and functions in accordance with the present inventionmay be implemented as specialized hardware or software executing in oneor more computer systems including computer system 102 shown in FIG. 1.As depicted, computer system 102 includes processor 110, memory 112, bus114, interface 116 and storage 118. Processor 110 may perform a seriesof instructions that result in manipulated data. Processor 110 may be acommercially available processor such as an Intel Pentium, MotorolaPowerPC, SGI MIPS, Sun UltraSPARC, or Hewlett-Packard PA-RISC processor,but may be any type of processor or controller as many other processorsand controllers are available. Processor 110 is connected to othersystem elements, including one or more memory devices 112, by bus 114.

Memory 112 may be used for storing programs and data during operation ofcomputer system 102. Thus, memory 112 may be a relatively highperformance, volatile, random access memory such as a dynamic randomaccess memory (DRAM) or static memory (SRAM). However, memory 112 mayinclude any device for storing data, such as a disk drive or othernon-volatile storage device. Various embodiments in accordance with thepresent invention may organize memory 112 into particularized and, insome cases, unique structures to perform the aspects and functionsdisclosed herein.

Components of computer system 102 may be coupled by an interconnectionelement such as bus 114. Bus 114 may include one or more physicalbusses, for example, busses between components that are integratedwithin a same machine, but may include any communication couplingbetween system elements including specialized or standard computing bustechnologies such as IDE, SCSI, PCI and InfiniBand. Thus, bus 114enables communications, for example, data and instructions, to beexchanged between system components of computer system 102.

Computer system 102 also includes one or more interface devices 116 suchas input devices, output devices and combination input/output devices.Interface devices may receive input or provide output. Moreparticularly, output devices may render information for externalpresentation. Input devices may accept information from externalsources. Examples of interface devices include keyboards, mouse devices,trackballs, microphones, touch screens, printing devices, displayscreens, speakers, network interface cards, etc. Interface devices allowcomputer system 102 to exchange information and communicate withexternal entities, such as users and other systems.

Storage system 118 may include a computer readable and writeablenonvolatile storage medium in which instructions are stored that definea program to be executed by the processor. Storage system 118 also mayinclude information that is recorded, on or in, the medium, and thisinformation may be processed by the program. More specifically, theinformation may be stored in one or more data structures specificallyconfigured to conserve storage space or increase data exchangeperformance. The instructions may be persistently stored as encodedsignals, and the instructions may cause a processor to perform any ofthe functions described herein. The medium may, for example, be opticaldisk, magnetic disk or flash memory, among others. In operation, theprocessor or some other controller may cause data to be read from thenonvolatile recording medium into another memory, such as memory 112,that allows for faster access to the information by the processor thandoes the storage medium included in storage system 118. The memory maybe located in storage system 118 or in memory 112, however, processor110 may manipulate the data within the memory 112, and then copies thedata to the medium associated with storage system 118 after processingis completed. A variety of components may manage data movement betweenthe medium and integrated circuit memory element and the invention isnot limited thereto. Further, the invention is not limited to aparticular memory system or storage system.

Although computer system 102 is shown by way of example as one type ofcomputer system upon which various aspects and functions in accordancewith the present invention may be practiced, aspects of the inventionare not limited to being implemented on the computer system as shown inFIG. 1. Various aspects and functions in accord with the presentinvention may be practiced on one or more computers having a differentarchitectures or components than that shown in FIG. 1. For instance,computer system 102 may include specially-programmed, special-purposehardware, such as for example, an application-specific integratedcircuit (ASIC) tailored to perform a particular operation disclosedherein. While another embodiment may perform the same function usingseveral general-purpose computing devices running MAC OS System X withMotorola PowerPC processors and several specialized computing devicesrunning proprietary hardware and operating systems.

Computer system 102 may be a computer system including an operatingsystem that manages at least a portion of the hardware elements includedin computer system 102. Usually, a processor or controller, such asprocessor 110, executes an operating system which may be, for example, aWindows-based operating system, such as, Windows NT, Windows 2000(Windows ME), Windows XP or Windows Vista operating systems, availablefrom the Microsoft Corporation, a MAC OS System X operating systemavailable from Apple Computer, one of many Linux-based operating systemdistributions, for example, the Enterprise Linux operating systemavailable from Red Hat Inc., a Solaris operating system available fromSun Microsystems, or a UNIX operating system available from varioussources. Many other operating systems may be used, and embodiments arenot limited to any particular implementation.

The processor and operating system together define a computer platformfor which application programs in high-level programming languages maybe written. These component applications may be executable,intermediate, for example, C−, bytecode or interpreted code whichcommunicates over a communication network, for example, the Internet,using a communication protocol, for example, TCP/IP. Similarly, aspectsin accord with the present invention may be implemented using anobject-oriented programming language, such as .Net, SmallTalk, Java,C++, Ada, or C# (C-Sharp). Other object-oriented programming languagesmay also be used. Alternatively, functional, scripting, or logicalprogramming languages may be used.

Additionally, various aspects and functions in accordance with thepresent invention may be implemented in a non-programmed environment,for example, documents created in HTML, XML or other format that, whenviewed in a window of a browser program, render aspects of agraphical-user interface or perform other functions. Further, variousembodiments in accord with the present invention may be implemented asprogrammed or non-programmed elements, or any combination thereof. Forexample, a web page may be implemented using HTML while a data objectcalled from within the web page may be written in C++. Thus, theinvention is not limited to a specific programming language and anysuitable programming language could also be used. Further, in at leastone embodiment, the tool may be implemented using VBA Excel.

A computer system included within an embodiment may perform additionalfunctions outside the scope of the invention. For instance, aspects ofthe system may be implemented using an existing commercial product, suchas, for example, Database Management Systems such as SQL Serveravailable from Microsoft of Seattle Wash., Oracle Database from Oracleof Redwood Shores, Calif., and MySQL from MySQL AB of Uppsala, Sweden orintegration software such as Web Sphere middleware from IBM of Armonk,N.Y. However, a computer system running, for example, SQL Server may beable to support both aspects in accord with the present invention anddatabases for sundry applications not within the scope of the invention.

Example System Architecture

FIG. 2 presents a context diagram including physical and logicalelements of distributed system 200. As shown, distributed system 200 isspecially configured in accordance with the present invention. Thesystem structure and content recited with regard to FIG. 2 is forexemplary purposes only and is not intended to limit the invention tothe specific structure shown in FIG. 2. As will be apparent to one ofordinary skill in the art, many variant system structures can bearchitected without deviating from the scope of the present invention.The particular arrangement presented in FIG. 2 was chosen to promoteclarity.

Information may flow between the elements, components and subsystemsdepicted in FIG. 2 using any technique. Such techniques include, forexample, passing the information over the network via TCP/IP, passingthe information between modules in memory and passing the information bywriting to a file, database, or some other non-volatile storage device.Other techniques and protocols may be used without departing from thescope of the invention.

Referring to FIG. 2, system 200 includes user 202, interface 204, datacenter design and management system 206, communications network 208 anddata center database 210. System 200 may allow user 202, such as a datacenter architect or other data center personnel, to interact withinterface 204 to create or modify a model of one or more data centerconfigurations. According to one embodiment, interface 204 may includeaspects of the floor editor and the rack editor as disclosed in PatentCooperation Treaty Application No. PCT/US08/63675, entitled METHODS ANDSYSTEMS FOR MANAGING FACILITY POWER AND COOLING, filed on May 15, 2008,which is incorporated herein by reference in its entirety and ishereinafter referred to as PCT/US08/63675. In other embodiments,interface 204 may be implemented with specialized facilities that enableuser 202 to design, in a drag and drop fashion, a model that includes arepresentation of the physical layout of a data center or any subsetthereof. This layout may include representations of data centerstructural components as well as data center equipment. The features ofinterface 204, as may be found in various embodiments in accordance withthe present invention, are discussed further below. In at least oneembodiment, information regarding a data center is entered into system200 through the interface, and assessments and recommendations for thedata center are provided to the user. Further, in at least oneembodiment, optimization processes may be performed to optimize coolingperformance and energy usage of the data center.

As shown in FIG. 2, data center design and management system 206presents data design interface 204 to user 202. According to oneembodiment, data center design and management system 206 may include thedata center design and management system as disclosed in PCT/US08/63675.In this embodiment, design interface 204 may incorporate functionalityof the input module, the display module and the builder module includedin PCT/US08/63675 and may use the database module to store and retrievedata.

As illustrated, data center design and management system 206 mayexchange information with data center database 210 via network 208. Thisinformation may include any information required to support the featuresand functions of data center design and management system 206. Forexample, in one embodiment, data center database 210 may include atleast some portion of the data stored in the data center equipmentdatabase described in PCT/US08/63675. In another embodiment, thisinformation may include any information required to support interface204, such as, among other data, the physical layout of one or more datacenter model configurations, the production and distributioncharacteristics of the cooling providers included in the modelconfigurations, the consumption characteristics of the cooling consumersin the model configurations, and a listing of equipment racks andcooling providers to be included in a cluster.

In one embodiment, data center database 210 may store types of coolingproviders, the amount of cool air provided by each type of coolingprovider, and a temperature of cool air provided by the coolingprovider. Thus, for example, data center database 210 includes recordsof a particular type of CRAC unit that is rated to deliver airflow atthe rate of 5,600 cfm at a temperature of 68 degrees Fahrenheit. Inaddition, the data center database 210 may store one or more coolingmetrics, such as inlet and outlet temperatures of the CRACs and inletand outlet temperatures of one or more equipment racks. The temperaturesmay be periodically measured and input into the system, or in otherembodiments, the temperatures may be continuously monitored usingdevices coupled to the system 200.

Data center database 210 may take the form of any logical constructioncapable of storing information on a computer readable medium including,among other structures, flat files, indexed files, hierarchicaldatabases, relational databases or object oriented databases. The datamay be modeled using unique and foreign key relationships and indexes.The unique and foreign key relationships and indexes may be establishedbetween the various fields and tables to ensure both data integrity anddata interchange performance.

The computer systems shown in FIG. 2, which include data center designand management system 206, network 208 and data center equipmentdatabase 210, each may include one or more computer systems. Asdiscussed above with regard to FIG. 1, computer systems may have one ormore processors or controllers, memory and interface devices. Theparticular configuration of system 200 depicted in FIG. 2 is used forillustration purposes only and embodiments of the invention may bepracticed in other contexts. Thus, embodiments of the invention are notlimited to a specific number of users or systems.

Data Center Assessment and Optimization Embodiments

In at least one embodiment, which will now be described, a tool isprovided that arranges a list of equipment (racks, coolers, UPS's,PDU's, etc.) in real time and displays the equipment in a cluster layoutmodel, such that the rack airflows and the cooling airflows get evenlydistributed in the cluster layout. FIG. 3 shows an example of a cluster300 of racks and coolers arranged in two rows A and B about a hot aislein a data center. In at least one embodiment, the layout shown in FIG. 3may be provided as an output of the tool, or the layout may be providedas an input, and the tool can arrange the equipment and coolers to meetspecified cooling criteria.

The cluster 300 includes 12 racks 302(a)-302(l), and four in-row coolers304. The racks in one example are industry standard 19-inch equipmentracks and the coolers are half-rack-width in-row coolers having a widththat is approximately half that of a standard equipment rack such ascoolers available from American Power Conversion Corporation of WestKingston, R.I., including In Row RC (IRRC), model ACRC100. However,embodiments of the invention may be used with other coolers andequipment racks as well. Further, the cluster shown in FIG. 3 is ahot-aisle cluster configured with the backs of the racks in Row A facingthe backs of the racks in Row B. In other embodiments, systems and toolsof embodiments of the invention may be configured for analysis andlayout of equipment racks in a cold-aisle cluster as well.

In one example, which will now be described, input data for a cluster isprovided by a user. In one embodiment, the input data is manuallyentered into the system, however, in other embodiments, the data may beprovided electronically from another system. The input data includes alist of racks with rack powers and airflow rates (cfm/kW), type ofcoolers with cooling airflow (cfm), power zone configurations and thedesired cooling redundancy or target air ratio (discussed in detailbelow). The power zone configurations describe the connectivity of racksor coolers to PDU and UPS power sources; this information is relevant tothe arrangement algorithm because there may be preferred equipmentlocations based on minimizing power cabling or other considerations.Using the input data, the tool calculates the required number of coolersbased on the total rack airflow and the desired cooling redundancy, andprovides a layout for the racks and coolers and any in-row PDU's andUPS's.

Table 1 provides a list of rack power and rack airflow for one examplewith the racks arranged in ascending order based on rack power.

TABLE 1 List of Rack Powers and Rack Airflow Sorted Rack Airflow RackPower Rack Airflow (kW) (cfm) 1 160 2 320 3 480 4 640 5 800 6 960 7 11208 1280

In one embodiment, the tool automatically arranges the racks using aprocess that involves two major steps; first, racks are arranged in thecluster, and second coolers are positioned in the cluster. In laying outthe racks, the racks are first paired and arranged in two rows A and Bsuch that the sum of airflow for each rack pair and total rack airflowof Row A and Row B are equal or near equal. In pairing the racks, therack having the smallest rack airflow is paired with the rack having thelargest rack airflow, the rack having the second smallest rack airflowis paired with the rack having the second largest rack airflow, and soon, until all racks are paired up. The racks of each pair are arrangedwith one of the racks in Row A and the other rack in Row B with thebacks of the racks facing each other (in a cold aisle implementation,the fronts of the racks would face each other). For scenarios with anodd number of racks, the rack having the highest airflow is paired witha fictitious rack having no airflow.

The rack pairs are then arranged in Row A and Row B by first selectingthe first pair (smallest airflow rack and largest airflow rack) and thenplacing the other rack pairs alternatively on either side of the firstpair such that the smaller airflow rack of a pair gets the largerairflow rack of other pairs as its neighbors. Table 2 shows the racks ofTable 1 arranged according to the above-described process.

TABLE 2 Rack Pairs Arranged in Row A and Row B Row A, Rack airflow 4801280 320 800 (cfm) Row B, Rack airflow 960 160 1120 640 (cfm) Rack SliceAirflow 1440 1440 1440 1440 (cfm)

Next in the process, the total rack airflow for each rack pair (referredto herein as “rack slice”) is calculated. This total is shown in Table2. In the example, the airflow at each rack slice is 1440 cfm with totalrack airflow for each row equal to 2880 cfm, making a uniformdistribution of heating airflow in the cluster layout. The exampledescribed above is somewhat of an ideal situation, and in otherexamples, the airflows may not be equal, but the process works towardsbalancing the airflows across each slice and for each row.

More coolers may be needed in the cluster to capture the rack exhaustair if large rack airflow is located at the row ends. Therefore, in oneembodiment for cases when a rack at a row end has a larger airflow thanthat of a rack adjacent to it in the same row; the position of these tworacks is interchanged.

Table 3 shows the racks of Table 2 rearranged to move high airflow racksfrom the ends of the cluster. In Table 3, the position of the rack with800 cfm airflow is switched with that of the rack with 320 cfm at theright side of Row A and the position of the rack with 960 cfm airflow isswitched with that of the rack having 160 cfm airflow at the left sideof Row B.

TABLE 3 Rearrangement of Racks in Table 2 Row A 480 1280 800 320(airflow cfm) Row B 160 960 1120 640 (airflow, cfm)

After positioning the racks in the cluster, in one embodiment, theprocess performed by the tool determines the number and placement ofcoolers in the cluster. The number of coolers needed can be determinedbased on the total rack airflow and the target air ratio, and the numberof coolers needed is directly related to the desired cooling redundancy.A large value of target air ratio corresponds to high cooling redundancyand vice versa. For example, a larger value of target air ratio would beused to achieve an “n+2” cooling redundancy than would be required toachieve “n+1”. The number of coolers required in a cluster is calculatedusing Equation 1 below:No. of coolers=(Total Rack Airflow)*(AR_(Target))/(Single coolerairflow)  Equation (1)

In Equation 1, since, the number of coolers cannot be a fraction; theresult is rounded up to the next integer. Applying Equation (1) to theexample discussed above with reference to Table 3, using coolers having2900 cfm, and an AR_(Target) value of 1.2, results in a value of 2.38,rounded up to 3 coolers. The AR_(Target) is the target air ratio. Theair ratio is defined as the ratio of total cooling airflow to total rackairflow. The AR should be greater than 1 and in one embodiment, thevalue of AR_(Target) is 1.2. The three coolers are divided between RowsA and B based on the total rack airflow of the rows. In the example ofTable 3, the total airflow of the racks of Row A and that of Row B areequal, two coolers are arbitrarily assigned to Row A, and one cooler isassigned to Row B. If the rows were not of equal length, then thecoolers could be placed to make the rows of more equal length.

Next, the location of the cooler in the rows must be determined In oneembodiment, since the coolers have less ability to capture exhaust airfrom the racks if they are located at the ends of the cluster, the endsare not considered as a possible location for the coolers, andaccordingly, the coolers are placed between racks. For the example ofTable 3, there are three possible cooler locations in each row betweenracks. These locations are generally referred to as cooler slicesherein, and in general for a number r of rack pairs or slices in acluster, there are r−1 cooler slices. Also, more than one cooler may beincluded at each cooler slice. Table 4 shows the total combined airflowfor each rack slice for the example of Table 3, three possible coolerlocations j1, j2 and j3, and four rack slices i1, i2, i3 and i4.

TABLE 4 Rack Slice Airflow and Possible Cooler Locations CombinedAirflow Cool- Cool- Cool- 640 er(s) 2240 er(s) 1920 er(s) 960 i1 j1 i2j2 i3 j3 i4

The cooler(s) at each cooler slice location have a potential to capturehot exhaust air from each rack slice location. This potential decreaseswith the increase in distance between the cooler slice location and therack slice location and it increases with the increase in magnitude ofrack slice airflow or cooler slice airflow. The total airflow that canbe captured from a rack slice by coolers from all cooler slices can bedetermined using Equation 2.

for i=1, 2, . . . r (number of rack slices)

$\begin{matrix}{S_{i}^{*} = {\sum\limits_{j = 1}^{r - 1}\;{A_{ij}n_{j}^{c}}}} & {{Equation}\mspace{14mu}(2)}\end{matrix}$

where,

for j=1, 2, . . . (r−1) or number of cooler slices

$\begin{matrix}{{A_{ij} = \frac{y_{i}Q_{j}^{c}}{\sum\limits_{i = 1}^{r}\; y_{i}}},{y_{i} = \left\{ \begin{matrix}{S_{i},} & {{{for}\mspace{14mu}\left( {i - j} \right)} = {0\mspace{14mu}{or}\mspace{14mu} 1}} \\{\frac{S_{i}}{p^{({j - i})}},} & {{{for}\mspace{14mu}\left( {i - j} \right)} < 0} \\{\frac{S_{i}}{p^{({i - j - 1})}},} & {{{for}\mspace{14mu}\left( {i - j} \right)} > 1}\end{matrix} \right.}} & {{Equation}\mspace{14mu}(3)}\end{matrix}$

where,

-   -   AR is the Air Ratio, defined as the ratio of total cooling        airflow and the total rack airflow.    -   S_(i) is the rack slice airflow at i^(th) rack slice location.    -   S_(i)* is the amount of airflow that can be captured from i^(th)        rack slice by coolers at all cooler slices.    -   p is a constant (e.g. 2, 10 etc.). A large value for this        constant implies a drastic decrease in a cooler's capturing        effect with increasing distance between cooler and rack slices.        The value of p=10 is observed to be a reasonable choice for        practical cases and is used in at least some embodiments of the        invention.    -   n_(j) ^(c) is the number of coolers at j^(th) cooler slice        location.    -   Q_(j) ^(c) is the airflow rate of a cooler (e.g. 2900 cfm for        IRRC or “c” type coolers) at j^(th) cooler slice.    -   A_(ij) can be considered a “capture coefficient” as it relates        the number of coolers at any cooler slice to the amount of rack        airflow that can be captured at any rack slice.

In at least one embodiment, the tool provides a layout that distributesthe rack airflow and cooling airflow substantially evenly in the clusterlayout. With rack slice airflows evenly placed, the next step is toposition the coolers. This can be achieved by placing coolers such thatthe product of Air Ratio (AR) and rack slice airflow matches the airflowthat can be captured by coolers from a rack slice (calculated usingEquation (2)). Mathematically, it is a minimization problem with thefollowing cost function:

$\sum\limits_{i = 1}^{r}\;\left( {{ARXS}_{i} - S_{i}^{*}} \right)^{2}$

With the constraints

${\sum\limits_{j = 1}^{r - 1}\; n_{j}^{c}} = {{{{No}.\mspace{14mu}{of}}\mspace{14mu}{coolers}\mspace{14mu}{and}\mspace{14mu} 0} \leq n_{j}^{c} \leq {{{No}.\mspace{14mu}{of}}\mspace{14mu}{coolers}}}$

This problem is solved in some embodiments using standard optimizationalgorithms (e.g. by branch and bound method etc.). In anotherembodiment, a simple approach that is fast and computationallyinexpensive is used to solve the minimization problem. This approachwill now be described with reference to FIG. 4 which shows a flow chartfor a process 500 for determining the number of coolers at all coolerslices. In a first stage 502 of the process 500, a determination is madeas to whether there is only one cooler. If there is only one cooler,then at stage 504, the cooler is placed at a center cooler slicelocation, and at stage 542, the process 500 ends.

If there is more than one cooler at stage 502, then process 500 proceedsto stage 506 where a cooler is placed at the first slice location j=1.At 508, a determination is then made as to whether the amount of airflowthat can be captured from the 1^(st) rack slice by all of the placedcoolers (only one cooler at this point in the process) is greater thanthe product of the airflow from the first rack slice and the air ratioAR. If the outcome of determination block 508 is YES, then the optimumposition of the first cooler may not be at j=1, and at block 510, thefirst cooler is moved to the next cooler slice location and at 512, adetermination is again made as to whether the amount of airflow that canbe captured from the 1^(st) rack slice by all of the placed coolers(only one cooler at this point in the process) is greater than theproduct of the airflow from the first rack slice and the air ratio AR.Stages 510 and 512 are repeated until the outcome of stage 512 is NO,and then at stage 514 the first cooler is placed at the current j slice.Also, if the outcome of stage 508 is NO, then the process proceeds tostage 514. At stage 515, a determination is made as to whether allcoolers have been placed. If the outcome of stage 515 is YES, then theprocess proceeds to stage 536 and continues as described further below.

If the outcome of stage 515 is NO, then the process 500 proceeds tostage 516, where the second cooler is placed at the last cooler slicelocation on the right at location j=r−1 (where r is equal to the totalnumber of rack slices). At stage 518 a determination is then made as towhether the amount of airflow that can be captured from the r rack sliceby all of the placed coolers is greater than the product of the airflowfrom the r rack slice and the air ratio AR. If the outcome ofdetermination block 518 is YES, then the optimum position of the secondcooler may not be at j=r−1, and at block 520, the second cooler is movedto the next cooler slice location to the left (j=j−1) and at stage 522,a determination is again made as to whether the amount of airflow thatcan be captured from the r rack slice by all of the placed coolers isgreater than the product of the airflow from the r rack slice and theair ratio AR. Stages 520 and 522 are repeated until the outcome of stage522 is NO, and then at stage 524 the second cooler is placed at thecurrent j slice. Also, if the outcome of stage 518 is NO, the processproceeds to stage 524.

The process 500 then proceeds to stage 526 where a determination is madeas to whether all coolers have been placed. If the outcome of stage 526is NO, then the process moves to stages 528 and 530 where the nextcooler is placed at a cooler slice location which is adjacent to thelast used cooler slice location from the left side. At stage 532 adetermination is then made as to whether the amount of airflow that canbe captured from the j rack slice by all of the placed coolers isgreater than the product of the airflow from the j rack slice and theair ratio AR. If the outcome of determination block 532 is YES, then theoptimum position of the current cooler may not be at the currentlocation, and at block 530, the current cooler is moved to the nextcooler slice location to the right (j=j+1). Stages 530 and 532 arerepeated until the outcome of stage 532 is NO, and then at stage 534 thesecond cooler is placed at the current j slice. Stages 526 to 532 arerepeated until all coolers have been placed.

Once all coolers have been placed, then the process 500 proceeds tostage 536 where it is determined whether more than one cooler exists ateach cooler slice. If the outcome of stage 536 is YES, then the processmoves to stage 538, where a determination is made as to whether the rackairflows adjacent each cooler slice is greater than the combined airflowof multiple coolers at the cooler slice. This step helps to distributethe cooling airflow more evenly throughout the cluster by movingcooler(s) towards the middle of the cluster. If the outcome of stage 538is YES, then at stage 540 one of the coolers is moved to the next coolerlocation to the left, unless the current slice is the last slice. If theoutcome of stage 538 or 536 is NO, or after stage 540, then the processends at stage 542.

Table 5 shows the distribution of coolers between rack slices.

TABLE 5 Shows the Distribution of Coolers in Between Rack Slices Rackslice 640 1 IRRC 2240 1 IRRC 1920 1 IRRC 960 airflow (cfm) or “IRRC”coolers

Once the number of coolers required at all cooler slices is determined,the last step is to place the racks and coolers in a cluster layout. Thecooler(s) required at different cooler slices are divided between Row Aand Row B such that both rows are as close as possible to equal length.FIG. 5 shows the final layout for the example considered here. As can beseen, the racks and coolers are evenly distributed with all racks having100% capture index. Once the layout is determined, it can be displayedand the racks and coolers may be installed in the data center inaccordance with the layout.

In embodiments described above, tools are described for evaluating datacenters that contain CRACs and equipment racks. As readily understood byone of ordinary skill in the art, in other embodiments, processes andsystems may be used with cooling providers other than CRACs and withcooling consumers other than equipment racks.

In embodiments described herein, cluster layouts of coolers andequipment racks meeting cooling criteria are determined and presented toa user. In other embodiments, the layout determined may be used as aninput into an optimization algorithm to provide further optimization ofthe cooling performance of the cluster. The optimization algorithms usedmay be based on, for example, genetic algorithms or branch and boundmethods. Within the optimization algorithm, the cooling performance ofeach candidate layout may be determined from computational fluiddynamics, or real-time algorithms based on CVA, Superposition, NeuralNetworks, algebraic, PDA-CFD, etc. models. Embodiments of the inventionare useful with these more complex techniques as they can greatly reducethe time to perform an optimization, since the input to the algorithmsare solutions that meet the cooling criteria.

In certain examples discussed herein, solutions provided by tools mayprovide layouts described as optimized layouts or near-optimizedlayouts. While complete optimized layouts are not guaranteed, solutionsprovided by such tools are generated quickly and satisfy specifiedcriteria.

In embodiments of the invention, a specified cooling redundancy may beused as part of the cooling criteria, and the cluster layout may bedesigned to meet the cooling redundancy.

As readily understood by one of ordinary skill in the art given thebenefit of this disclosure, tools described herein may be used for coldaisle applications and for application that use raised floors withperforated tiles acting as the cooling providers. The perforated tilesmay be the sole cooling providers in the application or may be used inconjunction with in-row coolers. Further, the tools may be used with avariety of rack widths, including a cold aisle having a six foot aislecovered with three rows of perforated tiles.

In at least some embodiments of the invention discussed herein, theperformance of assessments and calculations in real-time refers toprocesses that are completed in a matter of a few seconds or less ratherthan several minutes or longer as can happen with complex calculations,such as those involving typical computational fluid dynamicscalculations.

Having thus described several aspects of at least one embodiment of thisinvention, it is to be appreciated various alterations, modifications,and improvements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe invention. Accordingly, the foregoing description and drawings areby way of example only.

What is claimed is:
 1. A computer-implemented method for providing alayout of equipment in a data center, the equipment including aplurality of equipment racks, and at least one cooling provider, themethod comprising: receiving data regarding airflow consumption for eachof the plurality of equipment racks and cooling capacity of the at leastone cooling provider; storing the received data; determining a layout ofthe data center; and displaying the layout of the data center, whereindetermining the layout includes: pairing each equipment rack of theplurality of equipment racks with another equipment rack of theplurality of equipment racks based on airflow consumption of each of theplurality of equipment racks to create a plurality of pairs of equipmentracks such that a greatest airflow consuming equipment rack is pairedwith a least airflow consuming equipment rack, a second greatest airflowconsuming equipment rack is paired with a second least airflow consumingrack, and a third greatest airflow consuming equipment rack is pairedwith a third least airflow consuming rack; and arranging the pluralityof pairs of equipment racks to form a two-row cluster of equipment racksbased on the airflow consumption of each of the plurality of equipmentracks wherein each pair of the plurality of pairs of equipment racksincludes an equipment rack in a first row of the cluster and anequipment rack in a second row of the cluster.
 2. The method of claim 1,further comprising determining a location of the at least one coolingprovider.
 3. The method of claim 2, wherein the at least one coolingprovider includes a plurality of cooling providers and whereindetermining the location further comprises determining a number of theplurality of cooling providers to be placed in the cluster based on adesired cooling redundancy.
 4. The method of claim 2, wherein arrangingthe plurality of pairs of equipment racks includes: identifying a rackpair having a greatest airflow consumption value, a rack pair having aleast airflow consumption value, and a rack pair having a second leastairflow consumption value; and positioning the rack pair having thegreatest airflow consumption value in a middle position of the cluster,arranging the rack pair having the least airflow consumption value at afirst end of the cluster, and arranging the rack pair having the secondleast airflow consumption value at a second end of the cluster.
 5. Themethod of claim 4, wherein determining the location of the at least onecooling provider includes determining an interior position for the atleast one cooling provider adjacent two equipment racks.
 6. The methodof claim 1, further comprising receiving information related to adesired cooling redundancy for at least one of the equipment racks, andwherein determining the layout includes determining a layout based atleast in part on the information related to a desired coolingredundancy.
 7. The method of claim 1, further comprising: determining afirst combined airflow consumption value for each pair of the pluralityof pairs of equipment racks; and determining a second combined airflowconsumption value for the equipment racks in each row of the two-rowcluster of equipment racks.
 8. The method of claim 7, wherein pairingfurther comprises pairing the plurality of equipment racks in thetwo-row cluster of equipment racks such that the first combined airflowconsumption value for each of the pairs of the plurality of pairs ofequipment racks is uniformly distributed for each pair of the pluralityof pairs of equipment racks and the second combined airflow consumptionvalue for the equipment racks in each row is uniformly distributedacross each row.
 9. The method of claim 8, further comprising:identifying an equipment rack at a row end having a larger airflow thanan adjacent equipment rack; and re-arranging the identified rack in thetwo-row cluster of equipment racks.
 10. The method of claim 1, whereinpairing each equipment rack of the plurality of equipment racks withanother equipment rack of the plurality of equipment racks includespairing the greatest airflow consuming equipment rack with a fictitiousequipment rack.
 11. A system for providing a layout of equipment in adata center, the equipment including a plurality of equipment racks, andat least one cooling provider, the system comprising: a display; astorage device; an interface; and a controller coupled to the display,the storage device and the interface and configured to: receive throughthe interface data regarding airflow consumption for each of theplurality of equipment racks and cooling capacity of the at least onecooling provider; store the received data in the storage device;determine a layout of the data center; and display the layout of thedata center on the display, wherein determine the layout includes:pairing each equipment rack of the plurality of equipment racks withanother equipment rack of the plurality of equipment racks based onairflow consumption of each of the plurality of equipment racks tocreate a plurality of pairs of equipment racks such that a greatestairflow consuming equipment rack is paired with a least airflowconsuming equipment rack, a second greatest airflow consuming equipmentrack is paired with a second least airflow consuming rack, and a thirdgreatest airflow consuming equipment rack is paired with a third leastairflow consuming rack; and arranging the plurality of pairs ofequipment racks to form a two-row cluster of equipment racks based onthe airflow consumption of each of the plurality of equipment racks,wherein each pair of the plurality of pairs of equipment racks includesan equipment rack in a first row of the cluster and an equipment rack ina second row of the cluster.
 12. The system of claim 11, wherein thecontroller is further configured to determine a location of the at leastone cooling provider.
 13. The system of claim 12, wherein arranging theplurality of pairs of equipment racks includes: identifying a rack pairhaving a greatest airflow consumption value, a rack pair having a leastairflow consumption value, and a rack pair having a second least airflowconsumption value; and positioning the rack pair having the greatestairflow consumption value in a middle position of the cluster, arrangingthe rack pair having the least airflow consumption value at a first endof the cluster, and arranging the rack pair having the second leastairflow consumption value at a second end of the cluster.
 14. The systemof claim 13, wherein determining the location for the at least onecooling provider includes determining an interior position for the atleast one cooling provider adjacent two equipment racks.
 15. The systemof claim 11, wherein the controller is further configured to receiveinformation related to a desired cooling redundancy for at least one ofthe plurality of equipment racks, and wherein determining a layoutincludes determining a layout based at least in part on the informationrelated to a desired cooling redundancy.
 16. The system of claim 11,wherein the controller is further configured to determine a firstcombined airflow consumption value for each pair of the plurality ofpairs of equipment racks and determine a second combined airflowconsumption value for the equipment racks in each row of the two-rowcluster of equipment racks.
 17. The system of claim 16, wherein pairingfurther comprises pairing the plurality of equipment racks in thetwo-row cluster of equipment racks such that the first combined airflowconsumption value for each of the pairs of the plurality of pairs ofequipment racks is uniformly distributed for each pair and the secondcombined airflow consumption value for the equipment racks in each rowis uniformly distributed across each row.
 18. The system of claim 17,wherein the controller is further configured to: identify an equipmentrack at a row end having a larger airflow than an adjacent equipmentrack; and re-arrange the identified rack in the two-row cluster ofequipment racks.
 19. The system of claim 11, wherein the controller isconfigured to pair the greatest airflow consuming equipment rack with afictitious equipment rack.
 20. A non-transitory computer readable mediumhaving stored thereon sequences of instruction including instructionsthat will cause a processor to: receive data regarding airflowconsumption for each of a plurality of equipment racks and coolingcapacity of at least one cooling provider contained in a data center;store the received data in a storage device; determine a layout of thedata center; and display the layout of the data center on a display,wherein determine the layout includes: pairing each equipment rack ofthe plurality of equipment racks with another equipment rack of theplurality of equipment racks based on airflow consumption of each of theplurality of equipment racks to create a plurality of pairs of equipmentracks such that a greatest airflow consuming equipment rack is pairedwith a least airflow consuming equipment rack, a second greatest airflowconsuming equipment rack is paired with a second least airflow consumingrack, and a third greatest airflow consuming equipment rack is pairedwith a third least airflow consuming rack; and arranging the pluralityof pairs of equipment racks to form a two-row cluster of equipment racksbased on the airflow consumption of each of the plurality of equipmentracks, wherein each pair of the plurality of pairs of equipment racksincludes an equipment rack in a first row of the cluster and anequipment rack in a second row of the cluster.